Hi Cruisey,
Do you know the rules that apply to your SMSF?
I know for 'normal' super funds you can usually have access to your super if you can show 'severe financial hardship' - this includes being on Centrelink payments for over 26 weeks.
The ATO website states that to release super benefits under 'severe financial hardship' you need to be satisfied that the member:
1. can't meet reasonable and immediate family living expenses, and
2. has been receiving relevant government income support payments for a continuous period of 26 weeks and was receiving that support at the time they applied to the trustees.
Sorry I don't have expertise in this area and someone on here might be able to provide more help, but if you go to Google and type in 'financial hardship and SMSF' lots of articles appear - including some ATO Rulings on this - hope this helps a bit and I'm sorry to hear about your wife and your situation.
Really hope things improve for you soon - and worst case scenario - if they do ask you to pay it back, ask to do a payment plan with the ATO - you can maybe pay it back in small payments over a period of time? I know a few people who have ATO debts and they usually will try to work with you and not make you homeless. Good luck